Approximately 6% of breast cancer (BC) patients present with primary metastatic disease (pmBC) at first diagnosis. The clinicopathological differences between tumours from patients who have metastatic disease and those who do not are unclear.

This study was an exploratory analysis of patients with pmBC treated in 8 German breast cancer centres between 1998 and 2010. Phenotypes were defined using the following immunohistochemical markers: oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (Her2). The control arm included the group of patients who had neither local recurrence nor distant metastases at a follow-up of at least 30months after initial diagnosis.

A total of 2214 patients were included. Of these, 1642 had non metastatic BC, and 572 had pmBC. Eighty-five patients (15%) with pmBC were diagnosed at stage T1. On multivariate analysis, factors associated with pmBC were as follows: positive lymph node status, grade 3, lobular histology and Luminal B phenotype (Her 2 positive). Of the sample, 197 patients (34%) with pmBC were diagnosed as stage T2, 90 patients (16%) were diagnosed as stage T3, and 200 patients (35%) were diagnosed as stage T4. Only positive lymph node status and grade 3 were reported as risk factors for distant metastases in patients with stage T3 and T4 cancer.

There are differences in the clinicopathological features among breast cancer patients with primary metastases and those without. Receptor expression and histological type play a minor role in the risk for metastasis in patients with stage T3 and T4 disease when compared to patients with T1 pmBC tumours. On initial diagnosis, lobular histology and Luminal B positivity (Her 2 positive) in T1 pmBC were determined to be risk factors for primary metastatic disease.